Heading east along the equator Simon arrives in Ecuador, where he travels in 4x4 vehicles along muddy roads and across a swollen river to reach the capital, Quito.

Here Simon makes the difficult climb to the top of the volcano Pichincha.

Simon presses on to the Colombian border, passing through its most dangerous and lawless area, where government forces regularly battle guerrilla rebels.

Mired in violence and at the centre of the global cocaine trade, Colombia is enduring the worst humanitarian crisis in the western hemisphere.

Simon is escorted through the conflict zone by a Colombian Army colonel, before trekking through the jungle to discover the other face of Colombia: endangered animals and a remote Indian tribe with a sacred equatorial monument to the "centre of the world".

In Brazil, speedboats take Simon across vast untouched tracts of the Amazon rainforest to meet remote indigenous tribes, some of whom are now suffering from unemployment and alcoholism.

Much of the rainforest in the equator zone in western Brazil is still pristine, and there are numerous tribes living in complete isolation. Several have never had contact with the outside world.

Simon then races east across Brazil to his final destination in time for the Pororoca wave: a tide that coincides with a full moon and sends a mini tsunami wave up the Amazon tributaries.

Experienced surfers (and complete amateur Simon) have one chance to ride the tidal bore, but Simon and the boat crew forget the wave happens twice a day and their large boat is nearly tipped into the river late on their last night.